Process for stabilizing colloidal systems



Patented May 17, 1927.

UNITED STATES; r

1,629,163. ersnr orricr.

WILLY o. HERRMANN Ann woLrRA season, or MUNICEI. GERMANY, essrsuoas 'ro CONSORTIUM FUIER ELExTRoonpMIsoHE mnusrmn. or MUNICH, GERMANY.

PROCESS FOR STABILIZING COLLOIDAL SYSTEMS.

No Drawing. Application filed July 1, 1926, Serial lilo. 119,383, and in Germany July 17, 1925.

The object of this invention isthe stabilization of colloidal systemsthrough the adhydroxides. sulphides, oilsorother dispersoids may .bexstabilized, .i. e recipitation. or

coagulation may be prevented, by additions of polymerized vinyl alcohol. Polymerized vinyl alcohol is a new composition of matter the preparationofwhich is described in our copending application Serial No. 44,410, filed July 17, 1925. x,

This polymer can be obtained by polymerizing vinyl compounds and decomposing these polymerized vinyl compounds by the action of alkaline reagents, e. polymerized vinyl acetate on treatment with alcoholic potash gives directly the polymerized vinyl alcohol as a voluminous powder. As an example of this preparation the following is given:

grams of potassium hydroxide are dissolved in 50 grams of ethyl alcohol in a vessel equipped with a stirrer. To this solution is added. with thorough agitation. 80 grams of ground polymerized vinyl acetate. After agitating about half an hour the precipitated polymer of vinyl alcohol is separated on a filter and dried.

This polymer of vinyl alcohol is a water soluble powder without odor, of white color and has the formula (CH CHOH)... Determination of the molecular weight according to the osmotic pressure method gives figures between 780 and 870 accordin to the formula (CH zcHol-n to CHOHL... We do not. however, wish to be limited to those polymers having this degree of polymerization. Solutions of polymerized vinyl alcohol. are suitable for the preparation or stabilizations of colloidal systems in various degrees of dispersion and in various dispersing mediums.

This discovery can be utilized by merely adding the polymerized vinyl alcohol so1ution to a colloidal so ution prepared by any of the usual methods, or. the colloid may be prepared in a solution of polymerized vinyl alcohol.

The polymerized vinyl alcohol protects the system against the action of electrolytes. Stable colloidal solutions of gold, silver, platinum. copper. metal hydroxides, metal sulphides and the like have been prepared by utilizing solutions of polymerized vinyl alcohol. Furthermore, stabilized suspensions-o-finely divided materials and emulsiolisiof liquidswhave been secured by the use -of"p0lym erizedfvinyl. alcohol-in the dispersing medium.

l 0 15. chloride were dissolved in a few drops of waterand adde'd to250 cc.

of a -.5%. iiaqueous"solution of polymerized vinyl alcohol. 20 cc. of commercial formaldehyde solution and 10 cc. of 2N sodium carbonate solution were now added. The purple red colour of the colloidal gold was immediately formed: a highly stable gold colloidal results. This colloidal solution was now purified by dialysis. This solution was absolutely unaltered after one year of inspeetion.

ll'aaample ll.

Example III.

An aqueous colloidal gold solution was prepared by an electric arc. A 10% aqueous solution of polymerized vinyl alcohol was added and a stable colloidal system resulted.

Example IV.

4 grams iron chloride were dissolved in a minimum of water'and then added to a 20% aqueous solution of polymerized vinyl alcohol. Ammonium sulphide was now added in excess. No precipitation occurred but a fine suspension formed which was purified by dialysis.

Example V.

A jelly was prepared from 10 grams polymerized vinyl alcohol and a small amount of water. This was now mixed with 8 grams trichlorethylene and finally 82 grams of large; the amounts of this to be used in any solution will vary and'wedonot'wish to be limited to any exactproportions nor to the.-

examples given:

Whabwe claim is: 1 A method of stabilizing a colloidal system which comprises mixing polymerized 'vinyl alcohol with said system.

2. A method elf-stabilizing an aq'ueous colloidal system which. comprises adding an" 1 aqueous solution of polymerized =v1nyl alcohol to said hydrosol.

3. Method ofpreyention of the precipitation or coagulation" of a dispersoid which comprises adding' polymerized "vinyl alcohol to the co'l-loillal system. I

4::- Mthod of prevention olitheprecipitation or coagulation of a d-ispersoid in an 'l-uqueous' colloidal system which comprises adding thereto an aqueous solution oi polymerized vinyl alcohol.

5. "Method of prevention of the precipita tion or coagulation of metallic disp'ersoid which comprises-adding polymerized vinyl alcohol to the colloidal system.

6: Method of-stabilizing anaqueous colloidal gold solution which comprises adding an aqueous solution of polymerized vinyl alcohol thereto.

71' -As a product of manufacture a colloidal solution containing polymerized vinyl alcohol: as a'protective colloid.

8. As uproduct of manufacture it hydrosol "containing polymerized -vinyl alcohol as a I protective colloid.

WVILLY O; HERRh IANN. l/VO'LFRAM HAEHNEL. 

